An automobile is provided with a turbo unit in order to make effective use of the exhaust energy thereof. The turbo unit is arranged to operate a turbocharger by means of the exhaust thereof, and the flow rate of the exhaust is controlled by a valve. Opening of the valve is controlled by a motor (actuator). As environmental measures in recent years, there has been demanded more strictly controlling the amount of exhaust fed to the turbocharger. Therefore, a motor for driving the valve is required to be controlled with a greater accuracy.
Such a vehicle motor is provided with a detecting unit for detecting the position of a shaft of the motor. As a detecting unit, e.g., a structure is disclosed in which, as shown in FIG. 5, a sensor magnet 103 is disposed on the side of a shaft 102 supported on the side of a motor main body of a motor 101 and a detecting Hall element 106 for detecting the sensor magnet 103 is disposed on a circuit board 105 supported on a case 104 located on the side of a circuit main body of the motor 101. To be more specific, a magnet support member 108 is fixed on the shaft 102 supported rotatably relative to a stator 107 of the motor 101, and the sensor magnet 103 is attached on the face of the magnet support member 108. It is noted that the rotation of the shaft 102 is converted into the rectilinear motion thereof, which contributes to an opening or closing movement of the valve.
On the other hand, the case 104 is internally provided with a plurality of pins 109, and the pins 109 support the circuit board 105 with extending therethrough. The case 104 is integrally coupled to the end of the stator 107 with hot wires. The Hall element 106 for detection on the circuit board 105 detects the sensor magnet 103 on the side of the shaft 102 to be rotated, thus detecting the amount of rotation of the shaft 102 to measure the amount of opening and closing of the valve.
In a currently known structure of a motor, the motor main body and the circuit main body are fabricated separately from each other as described above, and as not depicted, it is arranged that a terminal connected to a coil of the motor 106 is molded on the side of the stator 107 of the motor main body and a connector connected to an external system is molded to the case 104 on the side of the circuit main body. This is because a convenience of fabrication, assembly, and so on of the motor in the manufacture thereof is considered. Further, as discussed above, the case 104 of the circuit main body is connected integrally to the stator 107 side of the motor main body through the use of hot wires. In this context, as a motor structure similar to the above-discussed one, a structure where a board is disposed on a stator side is disclosed in Patent Document 1.
Patent Document 1: International Publication WO97/33359
FIG. 6 schematically illustrates a coupling relation between members of a motor of which the structure is shown in FIG. 5. As shown in FIG. 6, the accuracy with which the circuit board 105 is positioned is determined by the accuracy with which the case 104 and the stator 107 are coupled to each other. Therefore, even if the Hall element 106 for detection is accurately positioned in the circuit board 105 to be mounted thereon, the displacement of the Hall element can occur after the case 104 is coupled to the stator 107 side with hot wires.
Further, in a structure where a circuit board is disposed on side of the stator as disclosed in Patent Document 1, it is difficult to electrically connect the circuit board to an external terminal, and though the accuracy on control can be kept at the same level, the structure is inferior in durability as compared with a structure where an external terminal is insert-molded on the side of the connector; consequently, the number of components is increased, and working processes and quality assurance involved thereby are difficult.
The present invention is made to solve the above-described problems, and an object of the present invention is to provide a motor positioning structure such that with respect to a sensor magnet that is one constituent element of a detecting unit on the side of the motor main body in the motor, the other constituent element disposed on the side of the circuit main body thereof can be positioned accurately.